Lidar Measurements of Stratospheric and Tropospheric Aerosols at 1064 nm Using a New and Low-Noise Photomultiplier

摘要

Using a new type of photomultiplier (PMT) tube R3236 cooled to -30°C, and a photon counting method, lidar measurements of stratospheric aerosols and tropospheric aerosols above an altitude of 2.25 km were made at the fundamental wavelength ofλ=1064 nm of a Nd:YAG laser which is sensitive to aerosol scattering. The PMT R3236 was found to be useful even for measurements of stratospheric aerosols near the background level.The average of the integrated backscattering coefficient above tropopause was 3.3×10-5 sr-1 at Tsukuba (36.1°N, 140.1°E) during November through December 1988. Tropospheric aerosol layers in the free atmosphere were frequently observed and the altitude of the maximum scattering ratio of the aerosol layer varied for every measurement, compared with the stable stratospheric aerosol layer. Some tropospheric aerosol layers were confined by two inversion layers.